Pump and control therefor



Sept. 7, 1965 K. D. BROWN PUMP AND CONTROL THEREFOR 6 Sheets-Sheet 1 Filed Jan. 25. 1962 N mw O MR M D R A N E K ATTORNEYS.

Sept. 7, 1965 K. D. BROWN 3,204,861

PUMP AND CONTROL THEREFOR Filed Jan. 25, 1962 6 Sheets-Sheet 2 INVENTOR. KENARD D. BROWN ATTORNEYS Sept. 7, 1965 K. D. BROWN PUMP AND CONTROL THEREFOR 6 Sheets-Sheet 3 Filed Jan. 25, 1962 N m R w w@ w m 0 NS m m D. N9 M9 M0 A2 m IF m9 9 mm m \v! w K 5 mm mm km 1 m: W W B I I. /v m 7k: mmmml lmfil mm mm vw g \w: m: w m9 NB 2 ATTORNEYS Sept; 7, 1965 K. D. BROWN PUMP AND CONTROL THEREFOR 6 Sheets-Sheet 4 Filed Jan. 25, 1962 INVENTOR. KENARD D. BROWN ATTORNEYS Sept. 7, 1965 K. D. BROWN PUMP AND CONTROL THEREFOR 6 Sheets-Sheet 5 Filed Jan. 25, 1962 INVENTOR. KENARD D BROWN ATTORNEYS Sept. 7, 1965 K. D. BROWN 3,204,861

PUMP AND CONTROL THEREFOR Filed Jan. 25, 1962 6 Sheets-Sheet 6 INVENTOR.

KENARD D. BROWN ATTORNEYS United States Patent 3,204,861 PUMP AND CONTROL THEREFOR Kenard l). Brown, Denver, Colo. (1227 S. Willow St, Casper, Wyo.) Fiied Jan. 25, 1962, Ser. No. 168,675 11 Claims. (Cl. 230-92) This invention relates to vacuum pumps and to systems employing such pumps and particularly to an improved pump and control system for pumping large volumes of gas.

Many industrial processes require large volumes of gas to be pumped continuously and various types of pumps and blowers have been proposed or employed for this purpose. Certain of these applications require that relatively low pressures be maintained and conventional expansible chamber, displacement and centrifugal pumps have not proved entirely satisfactory for these applications. By way of example, it has been proposed to maintain relatively low pressures in oil wells to facilitate the production of oil but conventional equipment has proved to be uneconomical and difiicult to maintain in operation for this purpose. Another application of vacuum pumps occurs in the separation of water and material dissolved or suspended therein. Here it has been found difficult to maintain the required low pressures while removing large volumes of water vapor. Accordingly it is an object of this invention to provide an improved vacuum pump.

It is another object of this invention to provide an improved vacuum pump capable of the continuous pumping of large volumes of gas.

Another object of this invention is to provide an improved vacuum pump and control for pumping continuously large volumes of gas.

It is another object of this invention to provide an improved apparatus for maintaining low pressures in oil wells and the like.

It is another object of this invention to provide an improved pumping apparatus and control system for facilitating the production of viscous petroleum for oil wells and the like.

It is another object of this invention to provide an improved apparatus for effecting the evaporative separation of water and solids mixed or dissolved therein.

It is a further object of this invention to provide an improved evaporation and condensing apparatus for puri: fying liquids.

It is a still further object of this invention to provide an improved apparatus for effecting the evaporative purication of water on a large scale.

Briefly, in carrying out the objects of this invention in one embodiment thereof, a vacuum pump is provided which comprises a tank containing a body of liquid in which is immersed a pump having a rotor of the screw or helical type arranged in a cylinder or shroud closed at one end and opening into the tank at the other. The pump is provided with a gas inlet and a liquid inlet adjacent its closed end, the liquid inlet being arranged to admit liquid from the tank. The pump during operation produces a vortex in the shroud and the vortex is controlled by adjusting the liquid inlet opening. It has been found that by proper adjustment of the rate of recirculation of the liquid a highly effective pumping action is secured which is capable of maintaining a high vacuum (low gas intake pressure) when the liquid intake supply is regulated and will pump a high volume of gas. The pump ope-rates effectively as a vacuum pump and will maintain a vacuum in an oil well where it maintains a continuous andsteady pressure and greatly facilitates the Patented Sept. 7, 1965 production of oil. In another embodiment of the invention the pump is employed in combination with an evaporative purifying system for water and provides an efficient evaporative system for desalting sea water. The pump during operation generates heat and this heat is employed with the vacuum in one embodiment of the invention to heat viscous petroleum in a well and facilitate its production from the well.

The features of novelty which characterize this invention are set forth in the claims annexed to and forming a part of this specification. The invention itself, however, both as to its organization and method of operation will be better understood upon reference to the following description taken in connection with the accompanying drawings, in which:

FIG. 1 is an elevation view partly in section to show the interior illustrating a vacuum pump embodying the invention;

FIG. 2 is an enlarged sectional view of the shroud and rotor of the pump of FIG. 1;

FIG. 3 is a somewhat diagrammatic view partly in section illustrating an oil well heating system embodying the invention;

FIG. 4 is a view similar to that of FIG. 2 illustrating a water purifying system embodying the invention;

FIG. 5 is another view similar to FIG. 3 illustrating a water desalting system embodying the invention;

FIG. 6 is an elevation view partly in section illustrating a boat provided with a sea water desalting system embodying the invention; and

FIG. 7 is a sectional View taken along the line 7-7 of FIG. 6.

Referring now to the drawings, the vacuum pump shown in FIG. 1 includes a generally cylindrical closed tank 10 having its walls insulated as indicated at 11 and mounted on a supporting base 12. The tank is arranged to be filled with a liquid such as water to a predetermined level indicated at 13 and with a condensed petroleum liquid to a level 13a maintained by operation of a float valve 14 in a manner to be described below. In the lower portion of the tank and mounted on the left-hand wall as shown there is provided a pump 15 comprising a cylindrical sleeve or shroud 16 and a screw or helical rotor 17 mounted on a horizontal shaft 18 for rotation partly within the shroud. The diameter of the rotor is enough smaller than the internal diameter of the sleeve 16 to leave a substantial annular clearance space. The left end of the shroud adjacent the tank wall is closed while the right end opens into the tank. The rotor 17 extends a short distance into the shroud, the major portion of the screw lying outside the shroud.

Liquid is circulated from the tank through the pump 15 under control of a valve 20 for varying the water admitted to the shroud through an inlet 21 in the bottom wall thereof. Gas or vapor from a supply line 22, which may, for example, be connected to an oil Well (not shown) is admitted to the pump through a vapor inlet 23 in the top wall thereof. Both the liquid inlet 21 and the gas inlet 23 communicate with the pump 15 within a chamber 24 formed between the closed end of the shroud and the rotor 17. The shaft is journaled in bearings 25 and 26 and is driven by a suitable prime mover illustrated as an internal combustion engine 27.

When the rotor 17 is driven at a suitable speed, say 900 revolutions per minute, gas is drawn into the pump through the inlet 23 and a vortex forms about the shaft 18 decreasing in diameter toward the right as indicated by dotted lines in FIG. 2. The water or other liquid is forced outwardly by centrifugal force and forms an effective seal around the rotor. Condensible vapors are liquefied in the vortex and in the water in the tank, noncondensibles being released into and rising through the main body of liquid in the tank. In order to secure effective and eflicient operation of the pump it is necessary to adjust the liquid return through the inlet port 21 to secure its optimum setting for the conditions of operation. In the illustration the valve is of the gate type and is controlled manually by a wheel 28. When the optimum valve setting has been attained, large volumes of gas are drawn into the pump and condensed. The pump at this setting is capable of maintaining a relatively high vacuum while pumping large volumes of gas.

The rapid condensation of vapor by operation of the rotor 17 raises the level 13a of the petroleum liquid in the tank and a float which operates the valve 14 rises and opens the valve to discharge liquid until the level is restored. The discharged liquid is supplied to a production line or pipe 29 for use or transportation.

When the pump is operated to pump a petroleum gas well, for example, the heavier hydrocarbons are condensed in the liquid in the tank while the lighter hydrocarbons, non-condensible under the conditions of operation of the pump, are collected in the tank above the level of liquid therein. These gases rise into a dome 31 and are removed through pipes 32 and 33 or through a suitable pop off valve 31a. The pipe 32 may be employed to supply gas to the engine 27 to supplement or replace the usual fuel supply through a supply line 34. The line 33 is employed to supply cooling gas to the pump; this gas passes through a heat transfer unit 35, cooled by air or other suitable fluid, and is then returned to the pump through a heat exchanger 36 in the liquid in the lower portion of the tank and thence through a nozzle 37 into the chamber 24. The-operation of this heat transfer arrangement may be controlled by a valve 40 actuated automatically in response to the temperature of the liquid in the tank as determined by a temperature sensing element 41 located therein.

In this application of the vacuum pump it is desirable to maintain a relatively low temperature of the water in the tank and it is for this reason that the rotor 17 is confined only at the entrance of the shroud. As will be pointed out below, the enclosure of a substantial length of the rotor in the shroud results in the generation of a very substantial quantity of heat which is desirable for many applications of the invention. The cooler temperatures realized in the pump of FIG. 1 facilitate the condensation of the heavier hydrocarbons and the return of cooled gas through the line 33 further effects cooling of the liquid.

The diameter of the rotor determines the size of the vortex formed during the operation of the pump. For

. a given shaft speed the larger the diameter of rotor the larger the vortex and the greater the peripheral speed of the turns of the helix. The volumetric capacity of the pump is determined by the speed of the shaft and the length of pitch of the helix. It will thus be apparent that a wide range of design is available. The spacing of the rotor from the shroud or cylinder wall may also be varied within a relatively wide range dependent upon the application for which the pump is intended. In all cases the control of the admission of liquid to the pump cylinder is relatively critical and is adjusted to effect the optimum performance in each application and condition of operation.

For many applications of the pump of this invention it is desired to generate substantial quantities of heat, and FIG. 3 illustrates a system wherein such heat is employed to facilitate the production of relatively viscous petroleum. In this embodiment a pump assembly indicated generally at 45 and which is similiar to that shown in FIG. 1 is connected by a vacuum or suction line 46 to remove gas from a well casing 47, the suction line being connected in communication with the interior of the casing through a well head fitting 48. Liquid pe troleum is removed from the well by operation of a pump 50 connected by a sucker rod 50a to be driven by a horsehead 5%; the pump receives liquid from the formation and delivers it to a production stream or tube 51.

In order to heat the well fluids in the well, high temperature liquid is supplied from the tank 52 of the pump assembly 45 through a line 53 under control of an automatic valve 54 having a temperature sensing element 55 immersed in the liquid in the tank. The line 53 extends downwardly into the well between the casing and the tubing 51 so that the hot liquid flows downwardly alongside the production tube and heats the liquid petroleum flowing upwardly therethrough; the hot liquid thus flows down into the well and over the producing surface of the formation where it counteracts the refrigerating effect of the liquid vaporized under the low pressure; the liquid then flows upwardly with the well fluids through the tube 51. The vacuum pipe 46 maintains the well at low pressure during the operation of the pump 45 and greatly facilitates the production of the well fluids. The pump 45 maintains a steady suction line pressure and has been found very effective in increasing the rate of production from petroleum formations which have been relatively low rate producers.

The pump assembly 45 includes a pump 56 comprising a sleeve or shroud 57 and a helical rotor 58 mounted on a shaft 6! for rotation in the shroud by operation of an internal combustion engine 61. The shaft 60 is journaled in bearings 62 and 63 and the rotor 53 is positioned within the sleeve 57 substantially throughout its length, the rotor diameter being smaller than the internal diameter of the sleeve and providing an appreciable spacing therebetween. The shroud is closed at its right-hand end by a plate 64 and a suction chamber 65 is formed between the end plate and the rotor 58. This arrangement which provides a longer portion of the rotor inlthe shroud results in the generation of larger amounts of heat in the liquid which is thereby maintained at higher temperatures than in the embodiment of FIG. 1.

Liquid is admitted to the pump under control of a valve 66 which controls a passage from valve inlet 67 in the tank to a pump intake port 68. The valve has been illustrated as manually controlled by a hand wheel 70. Gas or vapor from the well flows through the suction line 46 to a vapor inlet or port 71 entering the chamber 65. It will be noted that both intake ports 68 and 71 enter the chamber 65 behind the last turn or blade of the rotor 58; this arrangement of the rotor and ports assures effective operation of the pump.

The bearing 63 adjacent the suction side of the pump is sealed by liquid circulated from the tank through a compartment 72 in the bearing assembly and thence to the pump intake. For this purpose liquid is drawn from an outlet 73 in the side of the tank through a pipe 74 to the compartment 72 and thence to the chamber 65 under control of a valve 75a through a conduit 75 opening adjacent the inlet of the valve 66. This prevents leakage of air into the suction side of the pump through the bearing 63.

In this application the liquid in the tank 52 is petroleum and other well fluids and is maintained at a level 76 by operation of a float valve 77 actuated by a float 78; whenever the liquid level falls sufliciently the float opens the valve and admits petroleum from the production line indicated at 51a through a connection 80.

Volatile petroleum components collect above the level of the liquid in the tank and fill a dome 81; these gases are removed from the dome through a line 82 and are supplied as fuel for the engine 61, excess gases being removed by a pop off valve 81a. Fuel gas may also be supplied through a second source indicated as a supply line 83.

Additional heat may be supplied to the liquid in the tank 52 from the hot exhaust gases of the engine or from its cylinder jacket cooling system; by way of example, a

The system well formaabove a predetermined value. thus operates to maintain a low pressure in the tion and simultaneously supply hot well fluid or other the same manner as the shaft of FIG. 3.

The sleeve 91 is closed at its left-hand end as illustrated which provides an intake chamber 97 between the left end of the rotor and the wall of the tank. The suction line 89 opens into the chamber 97 at a liquid from the tank 1s admitted condensation of vapors passing therethrough.

The bearing 95 is provided with a liquid seal similar of the valve 101 through a connection 105 controlled by a hand valve 106. This sealing arrangement prevents the the bearing assembly.

Liquid to be treated, which may for example be river water or sewage, is admitted to the system from a supply through a connection 107 and passes through a pipe 108 to an upright tower 109 which it enters withdrawal of liquid by the suction pressure in the line 89 which is connected in communication with the tank through a head fixture 113.

Heat is supplied to the liquid within the tower 109 through a heat exchanger 114 connected to receive heat transfer liquid through line engine 94 and to return the liquid through line 116. In addition, liquid is withdrawn from the tower 109 by operation of a pump 118 which discharges the liquid be heated as it passes through a heat exchanger 127 which receives fresh water or other purified liquid from a collecting tank 128. The collecting tank is connected to receive hot fresh water from the tank 86 through a line 129 and to supply liquid to the heat exchanger 127 through a connection 131 and thence to the pump inlet 98 through a line 132. The admission of water from the line 132 to the pump chamber 97 is controlled by a hand valve 124. The water cooled by heat exchange with the is substantially cooler and facilitates the production of lower pressures at the pump inlet. The production of lower pressures is further facilitated by insulating of this liquid through the line 89 by operation of the pump, the vapor thereby being separated from the foreign matter carried into the tower. The concentrated liquid then falls to the body of liquid within the tower and further portions are a connection 140.

A further temperature control is flowing from the line 107 to the supply line 108 and comprises a heat exchange coil 141 arranged in the tank 128 in heat exchange with the purified water therein together with a normally closed valve 142 and a normally open valve 143. The valves 142 and 143 are controlled in accordance with the temperature of the water provided for the liquid the tank 128 and picks up heat from the During the operation of the system illustrated in FIG. 4, large volumes of vapor are removed ficient and rugged arrangement for purif ing water containing solids.

water to produce pure water for domestic use or the like. A system for this purpose is illustrated in FIG. 5. In this system a vacuum pump of the closed tank type similar to that described in connecembodiments is employed. As illustrated, pump of this system comprises a closed tank 146 having a rotary pump 147 mounted therein below the normal level of liquid indicated at 148. The pump 147 is driven by an internal combustion en gine 149 having a shaft 151 mounted in bearings 152 and 153 and on which the helical rotor indicated at 154 is mounted. The rotor 154 rotates within a housing or shroud 155 which has an internal diameter substantially greater than that of the rotor and provides an inlet chamber 156 between the left-hand end of the housing and the left-hand end of the casing as shown.

During the operation of the system fresh or purified water collects in the tank 146 and is discharged through an overflow or outlet 146a, the tank being at atmospheric pressure as indicated by an outlet pipe 157 The overflowing fresh water collects in an accumulator or auxiliary tank 158 and is discharged therefrom for use through an overflow connection 160.

The pump system as just described in connected to evaporate water from an evaporating chamber comprising an upright tower 161 the outlet of which is connected to a closed header 162 as indicated at 163 and conducts the vaporized water through a steam separator 164 and outlet conduit 165 to an inlet or suction connection 166 of the pump 147. The suction line 166 is connected to the pump 147 in communication with the chamber 156 as in the arrangements of the pumps previously described.

Salt water to be purified is admitted to the system through a supply line 167 and normally flows through conduits 1-68 and 169 through parallel heat exchangers 170 and 171 to a line 172 connected to supply salt water to the tower 161. The inlet line 172 terminates in a nozzle or head 173 within the tower 161 and delivers the liquid into the zone above the normal liquid level in the tower at 174. The nozzle 173 sprays the salt water into the tower where a portion of it is flashed immediately into vapor, the remainder falling to the body of liquid at the bottom of the tower; the tower is heated by a heat exchanger 175 connected in the liquid cooling system of the internal combustion engine 149 by lines 176 and 177; this cooling system is similar to that of FIG. 4 and circulates a suitable liquid heated by the engine block or exhaust gases or both. The tower 161 is maintained under a vacuum or low pressure by operation of the pump 147 and withdrawn water vapor admitted to the pump is condensed by operation of the pump and added to the water within the tank 146. Any air or other non-condensible gases passing through the system may be removed through the outlet 157.

The tower 161 is made sufficient-l tall that the suction pressure created by the pump 1'47 cannot draw liquid from the body of liquid within the tower into the exhaust line 163. The height to which water can be raised by operation of a vacuum is dependent upon the atmospheric pressure since it is the diflerence between atmospheric pressure and pressure in the pump which determines the pressure difierence tending to force the liquid water upwardly through the tower 161. It is necessary to remove the concentrated solution or salt water from the tank and for this purpose an inverted-U or siphon 178 is provided which is connected to the bottom of the tower 161 at 180 and to a discharge line at its other end as indicated at 181. The height of the inverted-U 178 is made sufficient to prevent the drawing of air into the system from the loop during operation of the pump at its lowest suction pressure; the siphon provides the overflow for excess liquid within the body in the tower 161 and thus maintains the normal level 174 of the liquid in the tower. The loop 178 thus provides an overflow tor the tank while at the same time preventing the breaking of the vacuum pressure within the tower 161. The steam separator 164 is provided in the line 163 in order to retain particles of water which may reach the line 163 and allow them to evaporate before proceeding into the suction line 165.

During the operation of the system, should the temperature of the water within the tank 146 fall below a preselected value, a temperature sensing element 182 will cause operation of a pair of values 183 and 184 to close the direct communication between the inlet 167 and the 8 lines 168 arid 169'and to open communication between the line 167 and a heat transfer coil 185 within the tank 158. Upon this change in the circuits the salt water to be treated passes through the coil 185 in the tank 158 and is heated by the water in this tank before proceeding through the heat exchangers 170 .and'171 in the tank 146.

The system as illustrated also includes the sealing chamber for the bearing 153 as indicated at 190, this chamber being filled with water circulated from the tank 146 by operation of a supply line 191 connected to the lower portion of the tank 146 and conducting the liquid through the chamber to a connection 192 under control of a hand valve 193. This circulated water is supplied to the intake side of a value 193 which controls the recirculation of water from the tank 146 through the pump 147 in the same manner as the liquid intakes of the pumps described above.

During operation of the system the valve 194 is adjusted by a hand control indicated as a wheel 193 so that optimum conditions are realized. Under these conditions of operation low pressure is achieved in the suction line 166 and large amounts of heat are liberated into the water within the tank 146. This heat is avaliable to heat the supply water and facilitate the flashing of the salt water into steam within the tower 61. Under optimum conditions the vortex formed by the helical rotor 154 acts effectively to withdraw and condense the steam passing through the inlet conduit 166, the steam not condensed within the shroud 155 being condensed shortly after emerging from the shroud at the right end of the pump.

The system as illustrated in FIG. 5 makes it possible to provide efiective pumping and evaporation of water from sea water and the like without requiring that moving parts of the system be located in the salt water and subject to the heavy corrosion resulting therefrom. In the present installation it will be noted that the pump and \its bearings are all located where they are subject only to wetting by the fresh water produced by operation of the system.

The system of this invention may also be employed for installation on a ship or other ve'ssel such as a barge anchored offshore, and in FIGS. 6 and 7 a system of this type is illustrated. As shown in these figures a floating barge or other vessel 200 is provided with a cylindrical insulated tank 201 mounted to extend a substantial distance into the water below the vessel. In the lower portions of the tank there is arranged a pump 202 of the same general construction as the pumps previously described and which comprises a cylindrical sleeve or shroud 203 within which is mounted a helical rotor 204 driven by .an electric motor 205 by rotation of a shaft 206 mounted in suitable hearings in the walls of the tank structure. In the arrangement illustrated the motor 205 is located in an offset portion or housing formed at one side of the tank.

Access to the compartment in which the motor 205 is located may be had through a door 207 hinged at the bottom end of a vertical passage 208 within the tank and which is closed at the top by a plate 209 bolted to the top cover :of the tank. The tank 201 is arranged to hold a body of water filling the tank to the level of an overflow conduit 210 from which fresh water flows to a reservoir 211 and may be distributed through a suitable outlet indicated diagrammatically by the arrow 212. Water is recirculated through the pump shroud 203 from an inlet 213 under control of a valve 214 connected by operating rods 215 and 216 to a hand wheel 217 on the deck of the vessel. The vapor intake of the pump 202 which is indicated at 218 is connected through a suction line 220 and an inverted-U 221 to an inverted dome or bell 222 mounted on the vessel and having an open end 223 a substantial distance below the level of the sea. The side walls of the bell 222 are insulated as indicated at 224 in order to prevent undue cooling by the sea water or air surrounding the valve. A vertical wall 225' is mounted above the casing of the motor 205 and extends upward parallel to the wall of the tank 2M and in spaced relationship thereto to form a vertical chamber 226. The wall 225 is heat-insulated as indicated.

A multiplicity of parallel tubes 227 extend through the tank 201 and are open at both ends. These tubes slope upwardly as shown and, because of the heating of the sea water within the tubes by heat exchange with the hot water within the tank produced by operation of the pump 262, the sea water rises and enters the area 226 and flows upwardly and over the upper end of the wall 225 onto a sloping wall 228 which is hinged to the top of the wall 225 at 230. The slope of the wall 228 is arranged to be adjusted by operation of a suitable mechanism such as a hydraulic actuator indicated at 23-1. Under some conditions of operation the flow of sea water through the tubes 227 may be produced by movement of the vessel 200 through the water or by anchoring the vessel in a moving stream.

It will now be apparent that during the operation of the pump low pressure is maintained Within the bell 222 which constitutes the evaporating chamber of the system and the heated water will vaporize, the vapor being drawn into the pump and condensed. The tube 221 is thermally insulated and is made suffic-iently high to prevent the drawing of liquid through the tube, the height of this loop being of the order of thirty-five feet for this purpose. The water within the bell 222 is cooled on being vaporized and flows toward the left-hand side as viewed in FIG. 6 and thence downwardly, the circulating being facilitated further by operation of a propeller 232 driven by a suitable motor 233. The slope of the wall 228 may be controlled automatically by a motor device 234 arranged to actuate the hydraulic operator 231 when the temperature within the left end of the bell as sensed by a sensing element 235 falls below a predetermined value. The slope of the wall 228 is decreased when the tempera ture falls so that the heated water may accumulate more readily in the upper portion of the bell.

During the operation of the system as illustarted, the propeller 232 has been provided in order to eifect a positive flow of the water within the bell downwardly and out the bottom thereof. It will be understood, however, that there is a natural thermal flow due to the rising effect of the heated water within the chamber 226 and its movement over and down along the wall 228 as it is cooled and thence downwardly and out the bottom of the bell.

During the operation of the system as illustrated the sea water is drawn continuously through the tubes 227 and a portion of it is vaporized within the bell; the remainder is then returned to the sea. This provides an automatic arrangement for disposing of the concentrated solution produced by operation of the system and continuous operation and production or" large amounts of fresh or distilled water is effectively accomplished by the system.

All of the systems as described above employ the cylindrical shroud and helical rotor of applicants invention. As has been mentioned above, the effect of this motor may be varied by changing the portion of the rotor which is within the shroud, and greater cooling is accomplished by having a smaller portion of the rotor within the shroud so that the cooling effect of vapor drawn through the pump and expanded may be utilized and so that there is a minimum heating due to the compression or vortex forming characteristics of the helical rotor within the shroud. The adjustment of the valve for controlling the recirculation of water through the pump has been found to be critical, as mentioned above, and for this reason the adjustment is made in accordance with the particular conditions of operation for each application and conditien of operation at the time. Furthermore, the spacing between the helical rotor and the shroud is also selected to secure optimum conditions for any one application of the invention.

To further facilitate an understanding of the invention and by way of example and not by way of limitation, one pump embodying the invention was constructed which had the following dimensions:

The pump was mounted in a tank four feet five inches wide, six feet ten inches long and nine feet high filled with water to a height of seven feet and thus containing approximately 1300 gallons. The rotor was driven by a diesel engine at approximately 800 r.p.m. When the gas inlet supply conduit was closed the pump maintained a vacuum of 24 inches of mercury and the temperature of the water was observed to rise from 48 F. to 86 F. in eighteen minutes.

While the invention has been described in connection with specific constructions of the pumping unit and systems, various other applications and modifications will occur to those skilled in the art. Therefore it is not desired that the invention be limited to the specific constructions illustrated and described and it is intended by the appended claims to cover all modifications which fall within the spirit and scope of the invention.

I claim:

1. A vacuum pump comprising a tank having a body of liquid therein, a combined liquid and vapor pump of the single screw type in said tank below the level of liquid therein for discharging fluid into said body of liquid below its level in said tank, means providing an intake chamber for said pump, means below the level of liquid in said tank fior providing communication between said intake chamber and said tank and for admitting substantial quantities of liquid from said body to said pump, suction conduit means providing a vapor inlet for said intake chamber, means for driving said pump, and means for adjusting said communication means for controlling the rate of recirculation of liquid from said tank through said pump, and thereby controlling the volume of liquid in said pump and the effective capacity of the pump.

2. A vacuum pump comprising a tank, means providing a substantially cylindrical chamber in said tank having one end in open communication with the interior of said tank and its other end closed, a pump rotor spaced from the closed end of said chamber and mounted for rotation on a shaft substantially concentric with said chamber, a first inlet means for admitting vapor to said chamber in the space between said rotor and the closed end thereof, a body of liquid filling said tank to a level above said chamber, a second inlet means for admitting liquid from aid body to said space in said chamber, means for driving said pump rotor to circulate liquid through said chamber into said body of liquid below the surface thereof in said tank and to pump gas through said first inlet mean and into said body of liquid, and means for controlling the rate of flow of liquid through said second inlet means.

3. A vacuum pump as set forth in claim 2 wherein said rotor is in the configuration of an anger and is of a diameter providing a substantial space between the wall of said chamber and the periphery of said rotor.

4. A vacuum pump as set forth in claim 2 wherein said means for driving said rotor includes a shaft passing through the wall of said tank, and including means ro- 1 1 viding a closed chamber about said shaft adjacent said wall of said tank, and means for circulating liquid from said tank through said closed chamber and back to said tank whereby leakage of gas from outside said tank about said shaft is minimized.

5. A pump as set forth in claim 3 wherein said second inlet means is spaced axially from said auger.

6. A vacuum pump as set forth in claim 2 wherein said control means includes means responsive to a condition of the liquid in said tank for effecting change in the flow of liquid through said second inlet means.

7. A vacuum pump as set forth in claim 2 including means for maintaining said predetermined level of liquid in said tank.

8. A vacuum pump as set forth in claim 2 including heat exchange means in said tank for elfecting changes of the temperature of said body of liquid therein.

9. A vacuum pump as set forth in claim 8 including means responsive to the temperature of said iiquid for controlling the operation of said heat exchange means.

10. A vacuum pump as set forth in claim 2 wherein said tank is closed and including means for maintaining the liquid therein at aid redetermined level. i

11. A vacuum pump as set forth in claim 10 including means for removing vapor from the space above the level of liquid in said tank.

References Cited by the Examiner UNITED STATES PATENTS Abbott 230-92 Nana 230-92 Mathis 230-108 Leonard 230205 Miller 230204 Kien 230204 Kien 230207 Girdwood 230204 Folberth 230205 Tibbetts et a1 230205 Aldridge 230205 Montelius 230205 Alcock 230-207 Williamson 202-167 Williamson 202163 Chapman 2 202l74 Wilkinson 1031 Creed 1031 Bailey 230205 Bailey et a1. 230205 Schibbye 230205 LAURENCE V. EFNER, Primary Examiner.

JOSEPH H, BRANSON, JR., Examiner. 

1. A VACUUM PUMP COMPRISING A TANK HAVING A BODY OF LIQUID THEREIN, A COMBINED LIQUID AND VAPOR PUMP OF THE SINGLE SCREW TYPE IN SAID TANK BELOW THE LEVEL OF LIQUID THEREIN FOR DISCHARGING FLUID INTO SAID BODY OF LIQUID BELOW ITS LEVEL IN SAID TANK, MEANS PROVIDING AN INTAKE CHAMBER FOR SAID PUMP, MEANS BELOW THE LEVEL OF LIQUID IN SAID TANK FOR PROVIDING COMMUNICATION BETWEEN SAID INTAKE CHAMBER AND SAID TANK AND FOR ADMITTING SUBSTANTIAL QUANTITIES OF LIQUID FROM SAID BODY TO SAID PUMP, SUCTION CONDUIT MEANS PROVIDING A VAPOR INLET FOR SAID INTAKE CHAMBER, MEANS FOR DRIVING SAID PUMP, AND MEANS FOR ADJUSTING SAID COMMUNICATION MEANS FOR CONTROLLING THE RATE OF RECIRCULATION OF 